ICD-10-CM > O00-O9A > O30-O48 > O31 > O31.3 > O31.33 O31.33 Continuing pregnancy after elective fetal reduction of one fetus or more, third trimester Non-Billable/Non-Specific Codes O31.33X0..., not applicable or unspecifiedO31.33X1..., fetus 1O31.33X2..., fetus 2O31.33X3..., fetus 3O31.33X4..., fetus 4O31.33X5..., fetus 5O31.33X9..., other fetus